const Regex compilation

[sae3023]

I think compiling a &'static str into a regex is a pretty popular use case.

However, no const fn make(pattern: &'static str) -> Regex exists.
Is it impossible to implement?
Is it possible, but the payout is not high enough, since they are meant to be compiled once anyway?

Sorry if the question is dumb, I'm a noob.

[BurntSushi]

It is somewhat addressed here: #913

For the specific case of a const method, theoretically, one could implement a regex engine using Rust const, but certainly not the one in this crate. To a first approximation, in order for this crate to have a pub const fn new(pattern: &'static str) -> Regex, you would need to have most of the Rust language usable inside a const context. That is nowhere near the case today.

The issue I linked addresses the more general case of "compile time regex" and specifically, "a serialization format for a regex that enables cheap deserialization." Rust const is just one way of getting a compile time regex. There are other techniques, as that issue covers.